Contact structure with insulating cap and method for forming the same

ABSTRACT

A semiconductor device structure is provided. The semiconductor device structure includes a gate stack formed over a semiconductor substrate, a source/drain contact structure adjacent to the gate stack, and a gate spacer formed between the gate stack and the source/drain contact structure. The semiconductor device structure also includes a first insulating capping feature covering an upper surface of the gate stack, a second insulating capping feature covering an upper surface of the source/drain contact structure, and an insulating layer covering the upper surfaces of the first insulating capping feature and the second insulating capping feature. The second insulating capping feature includes a material that is different from a material of the first insulating capping feature. The semiconductor device structure also includes a via structure passing through the insulating layer and the first insulating capping feature and electrically connected to the gate stack.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. As the semiconductor industry has progressed into nanometer technology process nodes in pursuit of higher device density, higher performance, and lower costs, challenges from both fabrication and design issues have resulted in the development of three-dimensional designs, such as the fin field effect transistor (FinFET).

FinFETs are fabricated with a thin vertical “fin” (or fin structure) extending from a substrate. The advantages of a FinFET include a reduction of the short channel effect and a higher current flow.

Although existing FinFET manufacturing processes have generally been adequate for their intended purposes, they have not been entirely satisfactory in all respects, especially as device scaling-down continues. For example, it is a challenge to form reliable via and contact structures at smaller and smaller sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIGS. 1A to 1D illustrate perspective views of various stages of manufacturing a semiconductor device structure in accordance with some embodiments.

FIGS. 2A to 2Q illustrate cross-sectional representations of various stages of manufacturing a semiconductor device structure in accordance with some embodiments.

FIG. 3 illustrates a cross-sectional representation of a semiconductor device structure in accordance with some embodiments.

FIG. 4 illustrates a cross-sectional representation of a semiconductor device structure in accordance with some embodiments.

FIG. 5 illustrates a cross-sectional representation of a semiconductor device structure in accordance with some embodiments.

FIG. 6 illustrates a cross-sectional representation of a semiconductor device structure in accordance with some embodiments.

FIG. 7 illustrates a cross-sectional representation of a semiconductor device structure in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. It should be understood that additional operations can be provided before, during, and after the method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Embodiments for manufacturing semiconductor device structures are provided. The semiconductor device structures may include a gate stack and an adjacent source/drain contact structure over a semiconductor substrate. A first insulating capping feature is formed over a gate stack, and a second insulating capping feature including a material that is different from the material of the first insulating capping feature is formed over the source/drain contact structure. An insulating layer is formed over the first and second insulating capping features. The second insulating capping feature provides a hard mask property during etching a via opening in the first insulating capping feature. As a result, the source/drain contact structure can be prevented from being bridged with the via structure over the gate stack. In addition, the second insulating capping feature also provides etching selectivity from the insulating layer during the etching a via opening in the insulating layer above the source/drain contact structure. Therefore, the formation of an etch stop layer between the insulating layer and the second insulating capping feature can be omitted. As a result, the etching capability for the definition of the via opening can be improved. The height of the subsequently formed via structure over the source/drain contact structure can be reduced, thereby reducing the resistance of the via structures, so that the device performance is increased.

FIGS. 1A to 1D illustrate perspective views of various stages of manufacturing a semiconductor device structure and FIGS. 2A to 2Q illustrate cross-sectional representations of various stages of manufacturing a semiconductor device structure in accordance with some embodiments. In addition, FIGS. 2A to 2D illustrate the cross-sectional representations of the semiconductor device structure shown along line 2-2′ in FIGS. 1A to 1D in accordance with some embodiments. In some embodiments, the semiconductor device structure is implemented as a fin field effect transistor (FinFET) structure. As shown in FIGS. 1A and 2A, a substrate 100 is provided. In some embodiments, the substrate 100 is a semiconductor substrate, such as a bulk semiconductor, a semiconductor-on-insulator (SOI) substrate, or the like, which may be doped (e.g. with a P-type or an N-type dopant) or undoped. In some embodiments, the substrate 100 is a wafer, such as a silicon wafer. Generally, an SOI substrate includes a layer of a semiconductor material formed on an insulator layer. The insulator layer may be, for example, a buried oxide (BOX) layer, a silicon oxide layer, or the like. The insulator layer is provided on a substrate, typically a silicon or glass substrate.

Other substrates, such as a multi-layered or gradient substrate may also be used. In some embodiments, the semiconductor material of the substrate 100 includes silicon; germanium; a compound semiconductor including silicon carbide, gallium arsenic, gallium phosphide, indium phosphide, indium arsenide, and/or indium antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or a combination thereof. In some embodiments, the substrate 100 includes silicon. In some embodiments, the substrate 100 includes an epitaxial layer. For example, the substrate 100 has an epitaxial layer overlying a bulk semiconductor.

In some embodiments, the substrate 100 has a PMOS region for P-type FinFETs formed thereon and/or an NMOS region for N-type FinFETs formed thereon. In some embodiments, the PMOS region of the substrate 100 includes Si, SiGe, SiGeB, or an III-V group semiconductor material (such as InSb, GaSb, or InGaSb). The NMOS region of the substrate 100 includes Si, SiP, SiC, SiPC, or an III-V group semiconductor material (such as InP, GaAs, AlAs, InAs, InAlAs, or InGaAs).

Afterwards, a fin structure 102 and an isolation feature 104 are formed over the substrate 100, as shown in FIG. 1A in accordance with some embodiments. In some embodiments, the substrate 100 is patterned to form the fin structure 102. The fin structure 102 may have slope sidewalls and extend from the substrate 100. In some embodiments, the isolation feature 104 is a shallow trench isolation (STI) structure, and the fin structure 102 is surrounded by the isolation feature 104.

The isolation feature 104 may be formed by depositing an insulating layer (not shown) over the substrate 100 and recessing the insulating layer. The insulating layer for the formation of the isolation feature 104 may be made of silicon oxide, silicon nitride, silicon oxynitride, fluorosilicate glass (FSG), low-K dielectric materials, and/or another suitable dielectric material and may be deposited by a flowable CVD (FCVD) process, a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, or another applicable process.

Afterwards, dummy gate structures 115 a, 115 b, 115 c, and 115 d are formed across the fin structure 102 over the substrate 100 and cover the isolation feature 104, as shown in FIG. 1A in accordance with some embodiments. Each of the dummy gate structures 115 a, 115 b, 115 c, and 115 d may include a dummy gate dielectric layer 110 and a dummy gate electrode layer 112 formed over the dummy gate dielectric layer 110. In some embodiments, the dummy gate dielectric layer 110 is made of silicon oxide and the dummy gate electrode layer 112 is made of polysilicon.

Gate spacers 120 are formed on the opposite sides (e.g., sidewalls) of the dummy gate structures 115 a, 115 b, 115 c, and 115 d after the formation of the dummy gate structures 115 a, 115 b, 115 c, and 115 d, in accordance with some embodiments. Each of the gate spacers 120 includes a first spacer layer 116 adjacent to the corresponding dummy gate structure and a second spacer layer 118 adjacent to the first spacer layer 116, as shown in FIGS. 1A and 2A in accordance with some embodiments.

The first spacer layer 116 may be used for protecting dummy gate structures 115 a, 115 b, 115 c, and 115 d from damage or loss during subsequent processing. In some embodiments, the first spacer layers 120 are made of low-K dielectric materials, silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, or another applicable dielectric material. The second spacer layer 118 is formed on the corresponding first spacer layer 116 in accordance with some embodiments. In some embodiments, the second spacer layer 118 is made of a material that is different from that of the first spacer layer 116, and includes silicon nitride, silicon oxide, silicon carbide, silicon oxynitride, or another applicable material.

After formation of the gate spacers 120, source/drain features 130 are formed in the fin structure 104 adjacent to and exposed from the dummy gate structures 115 a, 115 b, 115 c, and 115 d, as shown in FIGS. 1A and 2A in accordance with some embodiments. In some embodiments, the source/drain structures 114 is formed by recessing the fin structure 102 exposed from the dummy gate structures 115 a, 115 b, 115 c, and 115 d and growing semiconductor materials in the formed recesses in the fin structure 102 by performing epitaxial (epi) growth processes. In some embodiments, the semiconductor device structure is an NMOS device, and the source/drain feature 124 includes Si, SiP, SiC, SiPC, or an III-V group semiconductor material (such as InP, GaAs, AlAs, InAs, InAlAs, or InGaAs), or the like. In some embodiments, the semiconductor device structure is a PMOS device, and the source/drain feature 124 includes Si, SiGe, SiGeB, or an III-V group semiconductor material (such as InSb, GaSb, or InGaSb), or the like. In some embodiments, the source/drain features 130 protrude above the isolation feature 104.

An insulating layer 132 is formed over the isolation feature 104 and covers the source/drain features 130 and the isolation feature 104 after the source/drain features 130 are formed, as shown in FIGS. 1B and 2B in accordance with some embodiments. The insulating layer 132 (which serves as an interlayer dielectric (ILD) layer) may be made of silicon oxide, tetraethyl orthosilicate (TEOS), phosphosilicate glass (PSG), borosilicate glass (BSG), boron-doped phosphosilicate Glass (BPSG), fluorosilicate glass (FSG), undoped silicate glass (USG), or the like. The insulating layer 132 may be deposited by any suitable method, such as a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PECVD) process, flowable CVD (FCVD) process, the like, or a combination thereof. The insulating layer 132 may be a single layer or include multiple dielectric layers with the same or different dielectric materials.

Afterwards, the dummy gate structures 115 a, 115 b, 115 c, and 115 d are removed and replaced by gate structures 140 a, 140 b, 140 c, and 140 d, as shown in FIGS. 1B and 2B in accordance with some embodiments. In some embodiments, each of the gate structures 140 a, 140 b, 140 c, and 140 d includes a gate dielectric layer 136, a gate electrode layer 138, and the gate spacers 120. The gate dielectric layer 136 may be made of metal oxides, metal nitrides, metal silicates, transition metal-oxides, transition metal-nitrides, transition metal-silicates, oxynitrides of metals, or other applicable dielectric materials.

In some embodiments, the gate electrode layer 138 is made of a conductive material, such as aluminum, copper, tungsten, titanium, tantalum, or another applicable material. Each of the gate structures 140 a, 140 b, 140 c, and 140 d may further include a work functional metal layer (not shown) between the gate dielectric layer 136 and the gate electrode layer 138, so that the gate structures 140 a, 140 b, 140 c, and 140 d have the proper work function values. An exemplary p-type work function metal layer may be made of TiN, TaN, Ru, Mo, Al, WN, ZrSi₂, MoSi₂, TaSi₂, NiSi₂, WN, or a combination thereof. An exemplary n-type work function metal layer may be made of Ti, Ag, TaAl, TaAlC, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, or a combination thereof.

Afterwards, the gate structures 140 a, 140 b, 140 c, and 140 d are recessed by etching, so as to form recesses 141, as shown in FIGS. 1C and 2C in accordance with some embodiments. During the etching, top portions of the gate dielectric layers 130 and the gate spacers 120 are also recessed, so that upper sidewalls of the insulating layer 132 are exposed by the recesses 141 in accordance with some embodiments. In some embodiments, each of the gate electrode layers 138 is further recessed by etching after the upper sidewalls of the insulating layer 132 are exposed, so that the recesses 141 are extended to form a T-shaped profile, as shown in FIG. 2C. As a result, the upper surface of each gate spacer 120 and the upper surface of each gate dielectric layer 130 are higher than the upper surface of the corresponding gate electrode layer 138, as shown in FIGS. 1C and 2C in accordance with some embodiments.

Afterwards, a conductive capping feature 142 is formed to cover each of the recessed gate electrode layers 138, as shown in FIGS. 1C and 2C in accordance with some embodiments. The conductive capping features 142 and the underlying gate electrode layer 138 form gate stacks of the gate structures 140 a, 140 b, 140 c, and 140 d. In some embodiments, the upper surface of each gate spacer 120 is higher than the upper surface of each gate stack, as shown in FIGS. 1C and 2C. In some embodiments, the conductive capping features 142 serve as etch stop layers or protective layers for protecting the gate electrode layers 138 from damage or loss during subsequent processing, and are made of a metal material, such as tungsten or fluorine-free tungsten.

After the conductive capping features 142 are formed, a gate cut process is performed to remove one or more gate stacks of the gate structures 140 a, 140 b, 140 c, and 140 d in accordance with some embodiments. In some embodiments, the gate stack of the gate structure 140 c is removed by etching during the gate cut process, as shown in FIGS. 1C and 2C. Afterwards, an insulating material 139 fills the space that is formed by the removal of the gate stack of the gate structure 140 c to form an insulating gate-cut structure 140 c′ in accordance with some embodiments. The insulating gate-cut structure 140 c′ includes the gate dielectric layer 136, the insulating material 139, and gate spacers 120 including the first spacer layers 116 and the second spacer layers 118.

The insulating material 139 may include silicon nitride, silicon oxynitride, or silicon carbon nitride, or the like. Alternatively, the insulating material 139 may include hafnium oxide (HfO₂), hafnium silicon oxide (HfSiO), hafnium tantalum oxide (HfTaO), hafnium titanium oxide (HfTiO), hafnium zirconium oxide (HfZrO), zirconium oxide, titanium oxide, aluminum oxide, and another applicable dielectric material.

After the insulating gate-cut structure 140 c′ is formed, insulating capping features 150 a, 150 b, 150 d, and 150 c are respectively formed in the recesses 141 (not shown and as indicated in FIGS. 1C and 2C) to cover the upper surfaces of the gate structures 140 a, 140 b, and 140 d, and the insulating gate-cut structure 140 c′, as shown in FIGS. 1D and 2D in accordance with some embodiments. In some embodiments, an insulating layer (not shown) used for formation of the insulating capping features 150 a, 150 b, 150 c, and 150 d is formed over the structure shown in FIGS. 1C and 2C and fills the recesses 141. For example, the insulating layer is made of a material different from the material of the insulating layer 132 and includes SiN, SiCN, SiOC, SiON, SiCN, or SiOCN. The insulating layer may be formed by performing a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PECVD) process, low-pressure CVD (LPCVD) process, an atomic layer deposition (ALD) process, or another applicable process. Afterwards, a polishing process is performed to remove the excess insulating layer above the insulating layer 132 in accordance with some embodiments. In some embodiments, such a polishing process is performed on the insulating layer until the insulating layer 132 is exposed and planarized. In some embodiments, the polishing process includes a chemical mechanical polishing (CMP) process. After the polishing process, the remaining insulating layer forms insulating capping features 150 a, 150 b, 150 c, and 150 d, as shown in FIG. 2D.

In some embodiments, the upper surfaces of the insulating capping features 150 a, 150 b, 150 c, and 150 d are substantially level with the upper surface of the insulating layer 132. The insulating capping features 150 a, 150 b, and 150 d serve as etch stop layers and protect the gate structures 140 a, 140 b, and 140 d in the subsequent manufacturing processes (e.g., etching processes).

After the insulating capping features 150 a, 150 b, 150 c, and 150 d are formed, a masking layer 154 is formed over the insulating layer 132 and the insulating capping features 150 a, 150 b, 150 c, and 150 d, as shown in FIG. 2E in accordance with some embodiments. In some embodiments, the masking layer 154 includes a tri-layer resist structure including a bottom layer, a middle layer, and a top layer. In order to simplify the diagram, only a flat layer (i.e., the masking layer 154) is depicted.

More specifically, the bottom layer is a first layer of the tri-layer resist structure. The bottom layer may contain a material that is patternable and/or have anti-reflection properties. In some embodiments, the bottom layer is a bottom anti-reflective coating (BARC) layer, such as a nitrogen-free anti-reflective coating (NFARC) layer. In some embodiments, the bottom layer is formed by a spin-on coating process, a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process, or another suitable deposition process. The middle layer is formed over the bottom layer and is a second layer of the tri-layer resist structure. The middle layer (which is also referred to as a hard mask layer) provides hard mask properties for the photolithography process. In addition, the middle layer is designed to provide etching selectivity from the bottom layer and the top layer. In some embodiments, the middle layer is made of silicon nitride, silicon oxynitride or silicon oxide and is formed by a spin-on coating process, a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process, or another suitable deposition process.

The top layer is formed over the middle layer and is a third layer of the tri-layer resist structure. The top layer may be positive photoresist or negative photoresist. In some other embodiments, the tri-layer resist structure includes oxide-nitride-oxide (ONO) layers.

Afterwards, the tri-layer resist structure (i.e., the masking layer 154) is patterned to form a self-aligned opening 155 which is formed through the masking layer 154 and the insulating layer 132 to expose the upper surfaces of some source/drain features 130, as shown in FIG. 2F in accordance with some embodiments. In some embodiments, the self-aligned opening 155 is formed by etching the masking layer 154 and the insulating layer 132 between the insulating capping features 150 a, 150 b, 150 c, and 150 d. During the etching of the insulating layer 132, the insulating capping features 150 a, 150 b, 150 c, and 150 d are used as etch masks, so as to define some source/drain contact regions between the gate structures. For example, the source/drain contact regions are between gate structures 140 a and 140 b, between gate structure 140 b and the insulating gate-cut structure 140 c′, and between the insulating gate-cut structure 140 c′ and the gate structure 140 d. Although some portions of the insulating capping features 150 a, 150 b, 150 c, and 150 d may also be removed during the etching for formation of the self-aligned opening 155, the gate structures 140 a, 140 b, and 140 d and the insulating gate-cut structure 140 c′ are still protected by the insulating capping features 150 a, 150 b, 150 c, and 150 d.

After the self-aligned opening 155 is formed, a salicide process may be performed to form salicide layers (not shown) over the exposed the upper surfaces of the source/drain features 130. The salicide layers may be formed by forming a metal layer over the upper surfaces of the source/drain features 130. Afterwards, an annealing process is performed on the metal layer so the metal layer reacts with the source/drain features 130. Afterwards, the unreacted metal layer is removed to form the salicide layers. Examples for forming the metal layer may include Ti, Co, Ni, NiCo, Pt, Ni(Pt), Ir, Pt(Ir), Er, Yb, Pd, Rh, Nb, TiSiN, and the like.

A conductive material 156 is formed over the masking layer 154 and fills the self-aligned opening 155 after the self-aligned opening 155 and the salicide layers (if presented) are formed, as shown in FIG. 2G in accordance with some embodiments. In some embodiments, the conductive material 156 is made of Ru, Ni, Rh, Al, Mo, W, Co, Cu, or metal compound, or the like. The conductive material 156 may be formed by a chemical vapor deposition (CVD) process, a physical vapor deposition, (PVD) process, an atomic layer deposition (ALD) process, an electroless deposition (ELD) process, an electrochemical plating (ECP) process, or another applicable process.

Afterwards, a polishing process is performed to remove the excess conductive material 156 above the insulating capping features 150 a, 150 b, 150 c, and 150 d, as shown in FIG. 2H in accordance with some embodiments. In some embodiments, such a polishing process is performed on the conductive material 156 until the insulating capping features 150 a, 150 b, 150 c, and 150 d are exposed and planarized. In some embodiments, the polishing process includes a chemical mechanical polishing (CMP) process.

After the polishing process, the masking layer 154 is removed and the remaining conductive material 156 forms a contact structure 158 a between and adjacent to the gate structures 140 a and 140 b, a contact structure 158 b between and adjacent to the gate structure 140 b and the insulating gate-cut structure 140 c′, and a contact structure 158 c between and adjacent to the gate structure 140 d and the insulating gate-cut structure 140 c′, as shown in FIG. 2H. Those contact structures 158 a, 158 b and 158 c are electrically connected to the corresponding source/drain features 130 and therefore they are also referred to as self-aligned source/drain contact structures or self-aligned source/drain electrodes.

Afterwards, the contact structures 158 a, 158 b, and 158 c are etched to form recesses passing through the insulating capping features 150 a, 150 b, 150 c, and 150 d, as shown in FIG. 2I in accordance with some embodiments. In some embodiments, portions of the contact structures 158 a, 158 b, and 158 c are etched, so that a recess 161 a is formed between the gate structures 140 a and 140 b, a recess 161 b is formed between the gate structure 140 b and the insulating gate-cut structure 140 c′, and a recess 161 c is formed between the insulating gate-cut structure 140 c′ and the gate structure 140 d. As a result, the upper surface 159 a of contact structure 158 a, the upper surface 159 b of contact structure 158 b, and the upper surface 159 c of contact structure 158 c are lower than the upper surface 157 a of the insulating capping feature 150 a, the upper surface 157 b of the insulating capping feature 150 b, the upper surface 157 c of the insulating capping feature 150 c, and the upper surface 157 d of the insulating capping feature 150 d. In some embodiments, the upper surfaces 159 a, 159 b, and 159 c are substantially level with the upper surfaces 142 a of the conductive capping features 142.

After the contact structures 158 a, 158 b, and 158 c are recessed, the recesses 161 a, 161 b, and 161 c are widened, as shown in FIG. 2J in accordance with some embodiments. In some embodiments, portions of the insulating capping features 150 a, 150 b, 150 c, and 150 d adjacent to the recesses 161 a, 161 b, and 161 c are removed by etching, so as to expose portions of the gate structures 140 a, 140 b, and 140 d and a portion of the insulating gate-cut structure 140 c′. The exposed portions of the gate structures 140 a, 140 b, and 140 d and the portion of the insulating gate-cut structure 140 c′ include the gate spacers 120 and the gate dielectric layers 136 on opposite sides of the contact structures 158 a, 158 b, and 158 c.

Afterwards, the exposed gate spacers 120 and the exposed gate dielectric layers 136 are also removed by etching in accordance with some embodiments, so that the upper surfaces of the etched gate spacers 120 and the etched gate dielectric layers 136 are substantially level with the upper surface 142 a of the conductive capping feature 142 (not shown and as indicated in FIG. 2I) and the upper surfaces 159 a, 159 b, and 159 c (not shown and as indicated in FIG. 2I) of the contact structures 158 a, 158 b, and 158 c. As a result, a widened recess 163 a is formed between the gate structures 140 a and 140 b, a widened recess 163 b is formed between the gate structure 140 b and the insulating gate-cut structure 140 c′, and a widened recess 163 c is formed between the insulating gate-cut structure 140 c′ and the gate structure 140 d, as shown in FIG. 2J.

After those widened recesses 163 a, 163 b, and 163 c are formed, insulating capping features are respectively formed in the widened recesses 163 a, 163 b, and 163 c (not shown and as indicated in FIG. 2J) in accordance with some embodiments. More specifically, a capping layer 170 is conformally formed over the structure shown in FIG. 2J to cover the insulating layer 132 and the insulating capping features 150 a, 150 b, 150 c, and 150 d and extend on and make direct contact with the sidewalls and the bottom of the widened recesses 163 a, 163 b, and 163 c, as shown in FIG. 2K in accordance with some embodiments. In some embodiments, the capping layer 170 is used for formation of the insulating capping features in the widened recesses 163 a, 163 b, and 163 c. In some embodiments, the capping layers 170 has a thickness T that is in a range from about 0.1 nm to about 30 nm. Moreover, the capping layer 170 is made of a material that is different from the material of the insulating capping features 150 a, 150 b, 150 c, and 150 d, the material of the gate spacers 120. Therefore, the subsequently formed insulating capping features (which include the capping layer 170) in the widened recesses 163 a, 163 b, and 163 c can provide etch selectivity from the insulating capping features 150 a, 150 b, 150 c, and 150 d and/or the gate spacers 120. As a result, such insulating capping features in the widened recesses 163 a, 163 b, and 163 c can provide a hard mask property during etching the capping feature 150 a, 150 b, 150 c, or 150 d for formation of a via opening therein.

In some embodiments, the capping layer 170 is made of SiON, Ta₂O₅, Al₂O₃, or ZrO₂. In some other embodiments, the capping layer 170 is made of Al-containing oxide, N-containing oxide, Hf-containing oxide, Ta-containing oxide, Ti-containing oxide, Zr-containing oxide, La-containing oxide, or another metal-containing oxide or high-K (e.g., K>5) dielectric material. The capping layer 170 may be formed by performing a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PECVD) process, low-pressure CVD (LPCVD) process, an atomic layer deposition (ALD) process, or another applicable process.

After the formation of the capping layer 170, a capping layer 172 is formed over the capping layer 170 and fills the widened recesses 163 a, 163 b, and 163 c, as shown in FIG. 2K in accordance with some embodiments. In some embodiments, the capping layer 172 is also used for formation of the insulating capping features in the widened recesses 163 a, 163 b, and 163 c. The capping layer 172 is made of a material that is different from the material of the capping layer 170, so as to provide etch selectivity from the capping layer 170. As a result, the capping layer 170 in the widened recesses 163 a, 163 b, and 163 c can serve an etch stop layer during subsequent formation of one or more via openings over the corresponding source/drain contact structure(s).

In some embodiments, the capping layer 172 is made of made of silicon oxide, tetraethyl orthosilicate (TEOS), phosphosilicate glass (PSG), borosilicate glass (BSG), boron-doped phosphosilicate Glass (BPSG), fluorosilicate glass (FSG), undoped silicate glass (USG), or the like. The insulating layer 160 may be formed by performing by any suitable deposition method, such as a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PECVD) process, flowable CVD (FCVD) process, physical vapor deposition, (PVD), atomic layer deposition (ALD), spin-on coating, the like, or a combination thereof.

Afterwards, a polishing process is performed to remove the excess capping layers 172 and 170 above the insulating layer 132 in accordance with some embodiments. In some embodiments, such a polishing process is successively performed on the capping layers 172 and 170 until the upper surface of the gate spacers 120 that are not adjacent to the contact structures 158 a and 158 b is exposed. In some embodiments, the polishing process includes a chemical mechanical polishing (CMP) process.

After the polishing process, the remaining capping layers 170 and 172 form insulating capping features 175 a, 175 b, and 175 c, as shown in FIG. 2L in accordance with some embodiments. In some embodiments, the insulating capping feature 175 a is in direct contact with the insulating capping features 150 a and 150 b, the insulating capping feature 175 b is in direct contact with the insulating capping features 150 b and 150 c, and the insulating capping feature 175 c is in direct contact with the insulating capping features 150 c and 150 d. In some embodiments, the upper surfaces of the insulating capping features 150 a, 150 b, 150 c, and 150 d are substantially level with the upper surfaces of the formed insulating capping features 175 a, 175 b, and 175 c. The insulating capping features 175 a, 175 b, and 175 c respectively cover and in contact with the upper surfaces 159 a, 159 b, and 159 c (not shown and as indicated in FIG. 2I) of the contact structures 158 a, 158 b, and 158 c. In some embodiments, the insulating capping features 175 a, 175 b, and 175 c have a height H equal to the depth of the widened recesses 163 a, 163 b, and 163 c (not shown and as indicated in FIG. 2J). The height H may be in a range from about 0.1 nm to about 50 nm.

In each of the insulating capping features 175 a, 175 b, and 175 c, the capping layers 170 has a U-shaped profile, so that the opposite sidewalls and the bottom of the capping layers 172 is covered by the capping layers 170. The capping layers 172 in each of the insulating capping features 175 a, 175 b, and 175 c serves as an etch stop layer in the subsequent manufacturing processes (e.g., etching processes).

After the insulating capping features 175 a, 175 b, and 175 c are formed, an insulating layer 180 is formed over and covers the insulating layer 132, the insulating capping features 150 a, 150 b, and 150 c, 150 d, 175 a, 175 b, and 175 c, as shown in FIG. 2M in accordance with some embodiments. The insulating layer 180 may include a single layer or multilayers and is made of SiO₂, SiOC, ZrO₂, HfO₂, or another applicable dielectric material, or a combination thereof. The insulating layer 180 may serve as an interlayer dielectric (ILD) layer. In some embodiments, the insulating layer 180 is made of a material that is different from the capping layer 170. In some embodiments, the insulating layer 180 is made of a material that is the same as that of the capping layer 172. For example, the insulating layer 180 is made of silicon oxide, tetraethyl orthosilicate (TEOS), phosphosilicate glass (PSG), borosilicate glass (BSG), boron-doped phosphosilicate Glass (BPSG), fluorosilicate glass (FSG), undoped silicate glass (USG), or the like. The insulating layer 160 may be formed by performing by any suitable deposition method, such as a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PECVD) process, flowable CVD (FCVD) process, physical vapor deposition, (PVD), atomic layer deposition (ALD), spin-on coating, the like, or a combination thereof.

After the insulating layer 180 is formed, a via opening 181 that passes through the insulating layer 180 and the insulating capping feature 150 a is formed, so as to expose the upper surface 142 a (not shown and as indicated in FIG. 2I) of the gate stack in the gate structure 140 a, as shown in FIG. 2N in accordance with some embodiments. In some embodiments, the via opening 181 corresponding to the gate structure 140 a is formed by performing photolithography and etching processes. For example, an etching process may be performed in the insulating layer 180 using the insulating capping feature 150 a as an etch stop layer, so that an opening through the insulating layer 180 is formed to expose a portion of the insulating capping feature 150 a.

Afterwards, the exposed portion of the insulating capping feature 150 a is etched, so as to extend the via opening 181 and expose the upper surface of the gate structure 140 a (e.g., the upper surface 142 a of the conductive capping feature 142 in the gate structure 140 a). During the etching of the via opening 181, the capping layer 170 of the insulating capping feature 175 a provides a hard mask property to prevent the contact structure 158 a adjacent to the gate structure 140 a from being damaged. As a result, the source/drain contact structure (i.e., the contact structure 158 a) can be prevented from being bridged with the subsequent via structure in the via opening 181 even if misalignment occurs in formation of the via opening 181.

After the via opening 181 is formed, a via opening 183 that passes through the insulating layer 180 and the insulating capping feature 175 c and a via trench opening 185 that passes through the insulating layer 180 and the corresponding insulating capping feature 175 b are formed, as shown in FIG. 2O in accordance with some embodiments.

In some embodiments, the upper surface 159 c (not shown and as indicated in FIG. 2I) of the contact structure 158 c is exposed through the via opening 183. Also, the upper surface 159 b (not shown and as indicated in FIG. 2I) of the contact structure 158 b is exposed through the via trench opening 185.

Similarly, the via opening 183 and a via trench opening 185 respectively corresponding to the contact structures 158 c and 158 b are formed by performing photolithography and etching processes. The via opening 181, the via opening 183, and the via trench opening 185 may have the same depth. As a result, the subsequently formed via structures respectively in the via opening 181, the via opening 183, and the via trench opening 185 have the same vertical heights.

Although the via opening 181 is formed prior to formation of the via opening 183 and the via trench opening 185, the via opening 183 and the via trench opening 185 may be formed prior to formation of the via opening 181, in accordance some embodiments. In addition, although the via opening 183 and the via trench opening 185 are formed simultaneously by the same photolithography and etching processes, the via opening 183 and the via trench opening 185 may be formed by respective photolithography and etching processes, in accordance some other embodiments.

Afterwards, a conductive material 190 is formed over the insulating layer 180 and fills the via openings 181 and 183, and the via trench opening 185, as shown in FIG. 2P in accordance with some embodiments. In some embodiments, the conductive material 190 is made of Ru, Ni, Rh, Al, Mo, W, Co, Cu, or metal compound, or the like. The conductive material 190 may be formed by a chemical vapor deposition (CVD) process, a physical vapor deposition, (PVD) process, an atomic layer deposition (ALD) process, an electroless deposition (ELD) process, an electrochemical plating (ECP) process, or another applicable process.

After the conductive material 190 is formed, a polishing process is performed on the conductive material 190 until the upper surface of the insulating layer 180 is exposed, in accordance with some embodiments. In some other embodiments, the exposed insulating layer 180 and the remaining conductive material 190 are further polished until the desired thickness of the insulating layer 180 is obtained, as shown in FIG. 2Q. In some embodiments, the polishing process includes a chemical mechanical polishing (CMP) process. After the polishing process, the remaining conductive material 190 in the via openings 181 and 183, and the via trench opening 185 forms conductive via structures 192, 194, and 196. As a result, the semiconductor device structure 10 a having the gate structures 140 a, 140 b, and 140 d, the contact structures 158 a, 158 b, and 158 c with insulating caps (e.g., insulating capping features 175 a, 175 b, and 175 c), and the via structures 192, 194, and 196 is formed.

In some embodiments, the via structure 192 is formed in and surrounded by the insulating layer 180 and the insulating capping feature 150 a and electrically connected to the gate structure 140 a via the conductive capping feature 142 that is formed between the gate electrode layer 138 and the via structure 192. In some embodiments, the via structure 194 and the via structure 196 are formed in and surrounded by the insulating layer 180 and respectively and electrically connected to the contact structures 158 c and 158 b. Moreover, the via structure 196 is overlapped with the contact structure 158 b, the gate structure 158 b, and the insulating gate-cut structure 140 c′, in accordance with some embodiments. In some embodiments, the via structures 192, 194, and 196 have upper surfaces that are substantially level with the upper surface of the insulating layer 180, as shown in FIG. 2Q.

Since the insulating capping feature 150 a and the capping layers 170 in the insulating capping features 175 a, 175 b, and 175 c can serve as etch stop layers during the formation of via openings 181 and 183 and the via trench opening 185 in the insulating layer 180, there is no need to form an etch stop layer between the insulating layer 180 and insulating capping features 150 a, 175 a, 175 b, and 175 c. As a result, the etching for the definition of via openings 181 and 183 and the via trench opening 185 can be simplified. In addition, since such an etch stop layer is omitted and the insulating layer 180 is thinned to the desired thickness, the height of the formed via structures 194 and 196 can be reduced. As a result, the resistances of the via structures 194 and 196 can be reduced to increase the device performance.

Many variations and/or modifications can be made to embodiments of the disclosure. FIG. 3 shows a cross-sectional representation of a semiconductor device structure 10 b, in accordance with some embodiments. The semiconductor device structure 10 b shown in FIG. 3 is similar to the semiconductor device structure 10 a shown in FIG. 2Q. In some embodiments, the materials, formation methods, and/or benefits of the semiconductor device structure 10 a shown in FIGS. 2A to 2Q may also be applied in the embodiments illustrated in FIG. 3, and are therefore not repeated.

Unlike the insulating capping feature 175 a in the semiconductor device structure 10 a shown in FIG. 2Q, the insulating capping feature 275 a in the semiconductor device structure 10 b shown in FIG. 3 further includes a capping layer 171 formed between the capping layer 170 and the capping layer 172, in accordance with some embodiments. In some embodiments, the formation of the insulating capping feature 275 a includes successively and conformally forming the capping layers 170 and 171 in the widened recess 163 a (not shown and as indicated in FIG. 2J). Afterwards, the capping layer 172 is formed over the capping layer 171 in the widened recess 163 a, so that the opposite sidewalls and the bottom of the capping layer 172 are covered by the capping layers 171 and 170.

In some embodiments, the capping layers 170, 171, and 172 are made of different materials. In some embodiments, the material of the capping layer 171 includes SiON, Ta₂O₅, Al₂O₃, or ZrO₂, Al-containing oxide, N-containing oxide, Hf-containing oxide, Ta-containing oxide, Ti-containing oxide, Zr-containing oxide, La-containing oxide, or another metal-containing oxide or high-K (e.g., K>5) dielectric material.

FIG. 4 shows a cross-sectional representation of a semiconductor device structure 10 c, in accordance with some embodiments. The semiconductor device structure 10 c shown in FIG. 4 is similar to the semiconductor device structure 10 a shown in FIG. 2Q. In some embodiments, the materials, formation methods, and/or benefits of the semiconductor device structure 10 a shown in FIGS. 2A to 2Q may also be applied in the embodiments illustrated in FIG. 4, and are therefore not repeated.

Unlike the insulating capping feature 175 a in the semiconductor device structure 10 a shown in FIG. 2Q, the capping layer 170 in the insulating capping feature 375 a in the semiconductor device structure 10 c shown in FIG. 4 has a reversed U-shaped profile, in accordance with some embodiments. The reversed U-shaped capping layer 170 covers the opposite sidewalls of the capping layer 172 and extends between the capping layer 172 and the insulating layer 180 to cover the top of the capping layer 172, in accordance with some embodiments. In some embodiments, the formation of the insulating capping feature 375 a includes forming the capping layer 172 in the widened recess that are formed between the insulating capping features 150 a and 150 b. Afterwards, the reversed U-shaped capping layer 170 is formed over the capping layer 172 in the widened recess, so that the opposite sidewalls and the top of the capping layer 172 are covered by the capping layer 170.

FIG. 5 shows a cross-sectional representation of a semiconductor device structure 10 d, in accordance with some embodiments. The semiconductor device structure 10 d shown in FIG. 5 is similar to the semiconductor device structure 10 a shown in FIG. 2Q. In some embodiments, the materials, formation methods, and/or benefits of the semiconductor device structure 10 a shown in FIGS. 2A to 2Q may also be applied in the embodiments illustrated in FIG. 5, and are therefore not repeated.

Unlike the insulating capping feature 175 a in the semiconductor device structure 10 a shown in FIG. 2Q, the capping layer 170 in the insulating capping feature 475 a in the semiconductor device structure 10 d shown in FIG. 5 covers the opposite sidewalls of the capping layer 172 and does not cover the bottom of the capping layer 172, in accordance with some embodiments. In some embodiments, the capping layer 170 has a height that is substantially equal to a height of the capping layer 172 and forms spacers on opposite sidewalls of the capping layer 172. In some embodiments, the formation of the insulating capping feature 475 a includes conformally forming the capping layer 170 in the widened recess that is formed between the insulating capping features 150 a and 150 b. Afterwards, the capping layer 170 on the bottom of each of the widened recess is removed to leave the capping layer 170 on the opposite sidewalls of the widened recess. Afterwards, the widened recess is filled with the capping layer 172, so that the opposite sidewalls of the capping layer 172 are covered by the capping layer 170.

FIG. 6 shows a cross-sectional representation of a semiconductor device structure 10 e, in accordance with some embodiments. The semiconductor device structure 10 e shown in FIG. 6 is similar to the semiconductor device structure 10 a shown in FIG. 2Q. In some embodiments, the materials, formation methods, and/or benefits of the semiconductor device structure 10 a shown in FIGS. 2A to 2Q may also be applied in the embodiments illustrated in FIG. 6, and are therefore not repeated.

Unlike the insulating capping feature 175 a in the semiconductor device structure 10 a shown in FIG. 2Q, the capping layer 170 in the insulating capping feature 575 a in the semiconductor device structure 10 e shown in FIG. 6 has a reversed U-shaped profile, in accordance with some embodiments. In some embodiments, the reversed U-shaped capping layer 170 is formed between the capping layer 172 and the contact structure 158 a and extends on the opposite sidewalls of the contact structure 158 a and extends between the capping layer 172 and the contact structure 158 a, so as to cover the upper surface of the contact structure 158 a. In some embodiments, the formation of the insulating capping feature 575 a includes partially removing portions (e.g., the second spacer layers 118) of the gate structures 140 a and 140 b that are exposed from the widened recess between the insulating capping features 150 a and 150 b. As a result, the opposite sidewalls of the contact structure 158 a is partially exposed. Afterwards, the reversed U-shaped capping layer 170 is conformally forming in the widened recess to cover the exposed portions of the opposite sidewalls and the top of the contact structure 158 a. Afterwards, the capping layer 172 is formed over the capping layer 170 in the widened recess.

FIG. 7 shows a cross-sectional representation of a semiconductor device structure 10 f, in accordance with some embodiments. The semiconductor device structure 10 f shown in FIG. 7 is similar to the semiconductor device structure 10 a shown in FIG. 2Q. In some embodiments, the materials, formation methods, and/or benefits of the semiconductor device structure 10 a shown in FIGS. 2A to 2Q may also be applied in the embodiments illustrated in FIG. 7, and are therefore not repeated.

Unlike the insulating capping feature 175 a in the semiconductor device structure 10 a shown in FIG. 2Q, the insulating capping feature 675 a in the semiconductor device structure 10 f shown in FIG. 7 has a rectangular profile and is formed of the capping layer 170, in accordance with some embodiments. In some embodiments, the rectangular insulating capping feature 675 a formed of the capping layer 170 fills the recess between the insulating capping features 150 a and 150 b, and the gate spacers 120 between the gate structures 140 a and 140 b protrude from the upper surface of the contact structures 142 of the gate structures 140 a and 140 b. As a result, such gate spacers 120 are formed between the insulating capping features 150 a and 675 a and between the insulating capping features 150 b and 675 a.

Embodiments of semiconductor device structures and methods for forming the same are provided. The formation of the semiconductor device structure includes forming a first insulating capping feature over a gate stack and forming a second insulating capping feature over a contact structure and adjacent to the gate stack. The second insulating capping feature includes a material different from that of the first insulating capping feature. Afterwards, an insulating layer covers the first and second insulating capping features. The second insulating capping feature serves a hard mask during the definition of a via opening in the insulating layer above the gate stack, thereby providing good isolation between the contact structure and the subsequently formed via structure over the gate stack. Therefore, the contact structure can be prevented from being bridged with the subsequently formed via structure. The first and second insulating capping features can serve as etch stop layers during the definition of via openings in the insulating layer. Therefore, there is no need to form an etch stop layer between the insulating layer and the first and second insulating capping features. As a result, the etching for the definition of via openings can be simplified. The height of the subsequently formed via structures can be reduced, thereby reducing the resistances of the via structures to increase the device performance.

In some embodiments, a semiconductor device structure is provided. The semiconductor device structure includes a gate stack, a source/drain contact structure, and a gate spacer formed over a semiconductor substrate. The source/drain contact structure is adjacent to the gate stack and the gate spacer is between the gate stack and the source/drain contact structure. The semiconductor device structure also includes a first insulating capping feature covering an upper surface of the gate stack and a second insulating capping feature covering an upper surface of the source/drain contact structure and adjacent to the first insulating capping feature. The second insulating capping feature includes a material that is different from a material of the first insulating capping feature. The semiconductor device structure also includes an insulating layer covering an upper surface of the first insulating capping feature and an upper surface of the second insulating capping feature. The semiconductor device structure also includes a via structure passing through the insulating layer and the first insulating capping feature and electrically connected to the gate stack.

In some embodiments, a semiconductor device structure is provided. The semiconductor device structure includes a fin structure over a semiconductor substrate, a contact structure electrically connected to a source/drain feature in the fin structure, and a gate structure across the fin structure and adjacent to the contact structure. The gate structure includes a gate electrode layer, a conductive capping feature formed over the gate electrode layer, and a gate spacer between the gate electrode layer and the contact structure. The semiconductor device structure also includes a first insulating capping feature formed over the gate structure, and a second insulating capping feature passing through the first insulating capping feature to contact an upper surface of the contact structure. The semiconductor device structure also includes an insulating layer formed over the first insulating capping feature and the second insulating capping feature. The semiconductor device structure also includes a via structure passing through the insulating layer and the first insulating capping feature and electrically connected to the conductive capping feature. The second insulating capping feature includes a material that is different from a material of the first insulating capping feature and a material of the insulating layer.

In some embodiments, a method for forming a semiconductor device structure is provided. The method includes forming a first insulating layer over a semiconductor substrate having a fin structure and forming two adjacent gate structures in the first insulating layer and across the fin structure. The method also includes covering each of the gate structures with a first insulating capping feature and etching the first insulating layer using the first insulating capping features as an etch mask, so as to form an opening between the gate structures. The method also includes forming a contact structure in the opening. The contact structure has an upper surface that is lower than upper surfaces of the first insulating capping features, so as to form a recess between the first insulating capping features. The method also includes widening the recess by removing portions of the first insulating capping features to expose portions of the gate structures. The method also includes forming a second insulating capping feature in the widened recess to cover the upper surface of the contact structure. The second insulating capping feature includes a material that is different from a material of the first insulating capping feature. The method also includes forming a second insulating layer over the first insulating layer and covering the first insulating capping feature and the second insulating capping feature. The method also includes forming a via structure passing through the second insulating layer and the first insulating capping feature.

The fins described above may be patterned by any suitable method. For example, the fins may be patterned using one or more photolithography processes, including double-patterning or multi-patterning processes. Generally, double-patterning or multi-patterning processes combine photolithography and self-aligned processes, allowing patterns to be created that have, for example, pitches smaller than what is otherwise obtainable using a single, direct photolithography process. For example, in one embodiment, a sacrificial layer is formed over a substrate and patterned using a photolithography process. Spacers are formed alongside the patterned sacrificial layer using a self-aligned process. The sacrificial layer is then removed, and the remaining spacers may then be used to pattern the fins.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

1. A semiconductor device structure, comprising: a gate stack formed over a semiconductor substrate; a source/drain contact structure formed over the semiconductor substrate and adjacent to the gate stack; a gate spacer formed between the gate stack and the source/drain contact structure; a first insulating capping feature covering an upper surface of the gate stack; a second insulating capping feature covering an upper surface of the source/drain contact structure and adjacent to the first insulating capping feature; an insulating layer covering an upper surface of the first insulating capping feature and an upper surface of the second insulating capping feature; and a via structure passing through the insulating layer and the first insulating capping feature and electrically connected to the gate stack, wherein the second insulating capping feature comprises a material that is different from a material of the first insulating capping feature.
 2. The semiconductor device structure as claimed in claim 1, wherein the second insulating capping feature extends over the gate spacer and comprises: a first capping layer; and a second capping layer covering opposite sidewalls of the first capping layer, wherein the second capping layer comprises a material that is different from a material of the first capping layer, a material of the insulating layer, and a material of the gate spacer.
 3. The semiconductor device structure as claimed in claim 2, wherein the second capping layer extends between the first capping layer and the source/drain contact structure to cover a bottom of the first capping layer.
 4. The semiconductor device structure as claimed in claim 2, wherein the second insulating capping feature further comprises: a third capping layer formed between the first capping layer and the second capping layer, wherein the third capping layer comprises a material that is different from the material of the first capping layer and the material of the second capping layer.
 5. The semiconductor device structure as claimed in claim 2, wherein the second capping layer extends between the first capping layer and the insulating layer to cover a top of the first capping layer.
 6. The semiconductor device structure as claimed in claim 1, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer formed between the first capping layer and the source/drain contact structure, and extending on opposite sidewalls of the source/drain contact structure, wherein the second capping layer comprises a material that is different from a material of the first capping layer, a material of the insulating layer, and a material of the gate spacer.
 7. The semiconductor device structure as claimed in claim 1, wherein the gate stack comprises: a gate electrode layer; and a conductive capping feature between the gate electrode layer and the first insulating capping feature, wherein the conductive capping feature has an upper surface that is substantially level with the upper surface of the source/drain contact structure.
 8. The semiconductor device structure as claimed in claim 1, wherein the first insulating capping feature is in direct contact with the second insulating capping feature, and an upper surface of the first insulating capping feature is substantially level with an upper surface of the second insulating capping feature.
 9. A semiconductor device structure, comprising: a fin structure over a semiconductor substrate; a contact structure electrically connected to a source/drain feature in the fin structure; a gate structure across the fin structure and adjacent to the contact structure, comprising: a gate electrode layer; a conductive capping feature formed over the gate electrode layer; and a gate spacer between the gate electrode layer and the contact structure; a first insulating capping feature formed over the gate structure; a second insulating capping feature passing through the first insulating capping feature to contact an upper surface of the contact structure; an insulating layer formed over the first insulating capping feature and the second insulating capping feature; a via structure passing through the insulating layer and the first insulating capping feature, and electrically connected to the conductive capping feature, wherein the second insulating capping feature comprises a material that is different from a material of the first insulating capping feature and a material of the insulating layer.
 10. The semiconductor device structure as claimed in claim 9, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer covering opposite sidewalls and a bottom of the first capping layer, wherein the second capping layer comprises a material that is different from a material of the first capping layer.
 11. The semiconductor device structure as claimed in claim 9, wherein the second insulating capping feature comprises: a first capping layer; a second capping layer covering opposite sidewalls and a bottom of the first capping layer; and a third capping layer formed between the first capping layer and the second capping layer, wherein the second capping layer comprises a material that is different from a material of the first capping layer and a material of the third capping layer.
 12. The semiconductor device structure as claimed in claim 9, wherein the gate spacer protrudes from an upper surface of the contact structure, so that the gate spacer is between the first insulating capping feature and the second insulating capping feature.
 13. The semiconductor device structure as claimed in claim 9, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer covering opposite sidewalls and a top of the first capping layer, wherein the second capping layer comprises a material that is different from the material of the first capping layer.
 14. The semiconductor device structure as claimed in claim 9, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer covering opposite sidewalls of the first capping layer, wherein the second capping layer has a height that is substantially equal to a height of the first capping layer and comprises a material that is different from a material of the first capping layer.
 15. The semiconductor device structure as claimed in claim 9, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer formed below the first capping layer and covering opposite sidewalls and an upper surface of the contact structure, wherein the second capping layer comprises a material that is different from a material of the first capping layer and a material of the gate spacer. 16-20. (canceled)
 21. A semiconductor device structure, comprising: a gate stack across a fin structure of a semiconductor substrate, comprising: a gate electrode layer; and a conductive capping feature over the gate electrode layer; a gate spacer formed over a sidewall of the gate stack; a contact structure formed over the fin structure and adjacent to the gate spacer, so that the contact structure is separated from the gate stack by the gate spacer, wherein the contact structure has an upper surface that is substantially level with an upper surface of the conductive capping feature and an upper surface of the gate spacer; a first insulating capping feature formed over the conductive capping feature; and a second insulating capping feature covering the gate spacer and the contact structure, wherein the second insulating capping feature is in direct contact with the first insulating capping feature, and has an upper surface that is substantially level with an upper surface of the first insulating capping feature.
 22. The semiconductor device structure as claimed in claim 21, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer covering opposite sidewalls of the first capping layer.
 23. The semiconductor device structure as claimed in claim 22, wherein the second insulating capping feature further comprises: a third capping layer formed between the first capping layer and the second capping layer.
 24. The semiconductor device structure as claimed in claim 22, wherein the second capping layer extends onto a top of the first capping layer.
 25. The semiconductor device structure as claimed in claim 21, wherein the second insulating capping feature comprises: a first capping layer; and a second capping layer formed between the first capping layer and the contact structure, and extending on opposite sidewalls of the contact structure. 